There is tremendous excitement surrounding solid-state batteries, particularly lithium-based all-solid-state batteries, since they provide a path towards safe, energy dense, and long-life batteries. In particular, sulfide materials have received significant attention as solid electrolytes. However, there remain challenges for adoption such as high interfacial resistance with electrodes and a narrower electrochemical stability window compared to oxide materials. One way to deal with these challenges is to use a combination of materials to act as barrier layers and separators.